Alismataceae in humid subtropical areas in southern Brazil

Abstract Alismataceae is a family of aquatic or semi-aquatic plants with a wide distribution in humid areas, occurring in tropical, subtropical and temperate regions. Although Brazil accounts for 50% of the entire species diversity of this family, there are many gaps in knowledge of the species and their distribution, especially in the southern region of the country. This paper presents the study of Alismataceae species in the Biomes Pampa and Atlantic Forest of Rio Grande do Sul, highlighting taxonomic, ecological and distribution aspects. This study was based on the morphological analysis of specimens deposited in online data repositories and herbaria, as well as specimens collected in wetlands in the extreme south of Brazil. Ten taxa were registered for Rio Grande do Sul state: Echinodorus grandiflorus, E. longiscapus, E. macrophyllus, E. reptilis, E. uruguayensis, Helanthium tenellum, Hydrocleys nymphoides, Sagittaria lancifolia, S. rhombifolia and S. montevidensis. As a result of this study, an identification key for the taxa, morphological descriptions, images of the species and distribution maps are presented. Ecological and phenological data are also provided.